One type of connector includes a frame with multiple passages and multiple contact assemblies lying in the passages. Each contact assembly has a lower end that is soldered to a trace on a circuit board. Each contact assembly has a contact tip that is biased upwardly by a spring, but which can be deflected downward considerably when engaging another device. Electrical contact between the contact device and the lower end of the sleeve can be established through engagement of the contact tip with the inside of the sleeve, or through the spring. Electrical connection though engagement of the contact tip with the sleeve has previously not been reliable. Electrical connection through the spring can result in unwanted inductance due to the multiple turns of the spring. A contact that provided good electrical connection between the contact tip and the bottom of the sleeve without substantial inductance, would be of value.
Soldering of the contact assembly lower ends to traces on the circuit board, can be accomplished by close control of the distance that the contact lower ends project below the frame lower surface, provided that the circuit board is not warped. However, if the circuit board is warped, then some solder connections may not be made. A system that assured that all contacts made soldered connections with traces on the circuit board, despite slight warping of the circuit board and/or connector frame would be value.
In accordance with one embodiment of the present invention, a connector is provided, of the type that has contact assemblies with contact tips, or pogo tips, that can be considerably depressed and lower ends for soldering to circuit boards, which assures good electrical connections between the top and bottom of each contact, and which enables reliable soldering of the connector lower ends to traces on a circuit board despite warping of the circuit board (and possibly the connector). Each connector assembly includes a sleeve, a pogo tip with a body slideable within an upper portion of the sleeve and with a post that extends above the sleeve, and a largely helical spring that biases the pogo tip upwardly while allowing it to be depressed a considerable distance.
The upper end of the spring is constructed to engage only one side of the lower end of the pogo tip, to cock the pogo tip, especially when it is depressed. This results in low resistance engagement between the body of the pogo tip and the inside walls of the sleeve, to thereby assure good electrical connection between the pogo tip and the sleeve. The spring is formed of material having a much higher resistivity than the resistivity of the sleeve material, to minimize the amount of current passing through the spring, and thereby minimize unwanted inductance.
The connector frame includes a quantity of elastomeric material with portions forming an interference fit with the sleeves of the contact assemblies. The contact assemblies are initially installed in the passages by pressing them down until the contact lower ends project below standoffs at the lower end of the frame. To solder the contact lower ends to traces on a circuit board, the connector frame is pressed down towards the circuit board, thereby causing the contact assemblies to shift upwardly despite interference fit with the elastomeric material. This assures that the bottom of each contact engages a corresponding trace on the circuit board, despite warpage of the circuit board (or possible warpage of the connector frame).
The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.